/**
 * Copyright (c) 2009 blurredVision
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 * associated documentation files (the "Software"), to deal in the Software without restriction, 
 * including without limitation the rights to use, copy, modify, merge, publish, distribute, 
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is 
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or 
 * substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT 
 * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT 
 * OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#ifndef __GUI_ICHANGELISTENER_H__
#define __GUI_ICHANGELISTENER_H__

#pragma once

#include <vector>

namespace gui {

class Component;

/// A change event. Called when the value of an item is changed ( i.e. Slider value )
struct ChangeEvent {
	Component* component;	///< The component, that triggered the event
};

/**
 * \ingroup coreGUI
 *
 * The IChangeListener interface.<br>
 * This interface can be implemented by any class that wishes to listen to change events. 
 * The listener must then be added using the addChangeListner method of the corresponding GUI element.
 *
 * \date 04-25-2007
 *
 * \author juckel
 *
 */
class GUI_EXPORT IChangeListener
{
public:
	/// Called by an observer when its value has changed
	virtual void onChangeEvent(const ChangeEvent &) {};
};


/**
 * \ingroup CoreEngine
 *
 * The IChangeObserver interface.<br>
 * When implemting the IChangeObserver, IChangeListener can be added and ChangeEvents can be thrown.
 *
 * \date 05-02-2007
 *
 * \author juckel
 *
 */
class GUI_EXPORT IChangeObserver
{
public:
	/// Add a listener to the observer
	virtual void addChangeListener(IChangeListener* cl);

	/// Remove a listener from the observer
	virtual void removeChangeListener(IChangeListener *cl);

	/// Remove all ChangeListeners
	/// TODO: bjoern: funktioniert das wirklich???
	virtual void deleteAllChangeListeners();

protected:
	/// Called upon changing of the value. Sends a ChangeEvent.
	virtual void valueChanged(Component *comp);

private:
	typedef std::vector<IChangeListener*>  cl_list;
	cl_list    m_lChangeListeners;		///< A list of change listeners
};

} // namespace

#endif
